The continuing reduction in size of microelectronic components, such as chips, diodes, laser sources and other such devices, and the reduction in transistor rise time, presents a formidable challenge to the packaging industry. In order to facilitate effective near-term utilization of the future microelectronic devices, the design and performance of first and second level packaging need a significant improvement with respect to the current state-of-the-art cooling technologies. Heat dissipation of various microelectronic devices exceeding 100 watts per cm2 and more is currently being considered in the art.
Various solutions for cooling microelectronic devices had been suggested in the literature and are known in the art. The following are examples of air-cooling systems.
In U.S. Pat. No. 4,447,842 (Berg) finned heat exchangers for electronic chips and cooling assembly were introduced. It features a pair of heat exchange fins mounted on the electronic chip, each projecting through a groove and into a channel of a cooling module, and kept in contact with a cooling surface of that module.
In U.S. Pat. No. 4,535,386 (Frey et. al.) a natural convection cooling system for electronic components was disclosed. The electronic components were to be mounted at the base of an enclosure, at an opening of an inner chimney, which separates the interior of the enclosure into forward and rearward compartments. The inner chimney serves to duct the heated air rising from the electronic components to the top of the enclosure. A heat exchanger is placed at the top of that enclosure, to cool the heated air, resulting in a cooler air movement downwardly, and thus establishing natural air turbulence within the enclosure.
Another cooling system was introduced in U.S. Pat. No. 4,158,875 (Tajima et. al.). In this patent the air cooling of the electronic components is achieved by a double-walled duct construction whereby air, as a coolant, is introduced, in a direction at high angles to the length of the heat generating electronic components.
In U.S. Pat. No. 4,837,663 (Zushi et. al.) a cooling system for an electronic apparatus was disclosed. It included a plurality of motherboards, each having a circuit board to be cooled, a blower for causing airflow, and a duct for directing the airflow between the motherboards.
To-date common cooling systems are not efficient enough when higher rates of heat dissipation from electronic components are considered, and as technology procedes to introduce micro electronic devices with higher performance parameters, with subsequently higher heat dissipation, there is a growing need for more efficient cooling systems. In U.S. Ser. No. 10/893,568 (Yassour, not yet published, incorporated herein by reference) there was disclosed a heat-exchanging device comprising a block made from a heat-conducting material with a plurality of cooling tubes whose inlets and outlets are distributed on an active surface, which is substantially opposite a heat-transfer surface placed adjacent a heat-dissipating electronic component. Each cooling tube is designed to direct a coolant fluid towards and then away from the heat-transfer surface, thus when coolant fluid passes through the cooling tubes it absorbs heat from the block and evacuates it away. The heat-exchanging device disclosed in that patent application appears to be dealing with the evacuation of heat locally rather than on a grand scale, thus achieving substantially greater efficiency over conventional electronic components cooling systems, which are generally of the grand-scale type.
It is a purpose of the present invention to provide a cooling system suitable for cooling a plurality of heat-dissipating electronic components residing on a single electronic board, or on a system of grouped electronic boards.
Another object of the present invention is to provide such a cooling system that is integral to that electronic board or group of boards.
Further objects and advantages of the present invention will become apparent after reading the present specification and claims and reviewing the accompanying drawings.